Reuben's Home Inspection Blog

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Storm chasers and defective roof installations

Have you ever noticed roofs with shingles popping up all over the place?  A common reason for this is the use of nails that are too short.  When there are popped nails all over the roof, it might be the sign of a defective roof installation; specifically, short nails.

Popped nail

The minimum fastener length for an asphalt shingle roof in Minnesota is 1-1/4".  This requirement comes from section R905.2.5 of the 2006 International Residential Code, which is part of the Minnesota State Building Code.  I underlined the part of this section that specifies the minimum fastener length.

R905.2.5 Fasteners. Fasteners for asphalt shingles shall be
galvanized steel, stainless steel, aluminum or copper roofing
nails, minimum 12 gage [0.105 inch (3 mm)] shank with
a minimum 3/8-inch (10 mm) diameter head, ASTM F 1667,
of a length to penetrate through the roofing materials and a
minimum of 3/4 inch (19 mm) into the roof sheathing. Where
the roof sheathing is less than 3/4 inch (19 mm) thick, the fasteners
shall penetrate through the sheathing. Fasteners shall
comply with ASTM F 1667.

In southern parts of the country where they don't need to deal with snow loads, it's acceptable to use 3/8" roof sheathing, which means it's also acceptable to use 1" roofing nails on asphalt shingles.  A 1" nail will fully penetrate through 3/8" roof sheathing, but it won't fully penetrate 1/2" sheathing.  The diagram below helps to illustrate this.

Short shingle nail diagram

When 1" nails are used to fasten asphalt shingles to 1/2" roof sheathing, only the very tip of the nail will penetrate the roof sheathing.  Over time, expansion and contraction of the roof sheathing can force the nail back up and out of the roof.  When this happens, the shingle tabs get lifted up.  On three-tab shingles, these lifted areas are often visible from the ground.

Lifted shingles

To determine if the wrong nails were used, just pull out one of the popped nails.  When 1" nails are used, the nails have frequently worked themselves so far out of the sheathing that it doesn't take much effort to pull the nail right of the roof by hand.  If that doesn't work, a pliers can usually be used to grab the head and pull the nail out without causing any damage to the shingle below.

one-inch roofing nail

The other way to determine if the proper nails were used is to look in the attic; if the roof has 1/2" sheathing, you should be able to see the nails sticking through in to the attic.  The photo below shows proper 1-1/4" nails sticking through the roof sheathing on the attic side.

proper nail visible in attic

If all you can see is the very tip of the nails and you have 1/2" sheathing, this is a problem.  Of course, if the roof sheathing consists of 1" roof boards, it's acceptable for the nails to not penetrate the sheathing.

When too short of nails have been used at the shingles, it's a defective roof installation that will be prone to popped nails and shingles coming loose.  According to the roof gods in Minnesota, this is a common installation defect that happens with storm-chasing roof repair companies.  You get a storm-chasing roofing crew that's used to 'southern' rules for roofs, and they install the roof with 1" shingles, just like they're used to doing.  The moral of the story is to avoid storm-chasing roof repair companies that go knocking door-to-door.  Hire a reputable local company instead.

Once again, this is one of those defects that you shouldn't expect the municipal (city) inspector to catch; they usually don't walk on roofs, and they almost certainly won't lift shingles to find nailing defects.  If you have an especially savvy inspector, however, they might find a short nail or two laying in the gutter, which might prompt them to start asking more questions.

RELATED POST: Improper Shingle Nailing

Reuben Saltzman, Structure Tech Home Inspections

        

Comment balloon 17 commentsReuben Saltzman • July 17 2012 03:21AM

Comments

Good morning Reuben,

Your posts are always so educational and written so we can understand! Great comparison to see the length of the nails..I've had inspectors tell us that but your visuals really put things in perspective!

Posted by Dorie Dillard CRS GRI ABR, Serving Buyers & Sellers in NW Austin Real Estate (Coldwell Banker United Realtors® ~ 512.346.1799) over 6 years ago

Reuben, at first I though why would anyone use short nails. Your explanation makes sense because the storm chasers use the shorter nails in the South where longer nails aren't required. Something to keep in mind. Thanks.

Posted by Michael Setunsky, Your Commercial Real Estate Link to Northern VA over 6 years ago

Just like putting lipstick on a pig.  Sure, it looks good temporarily but will it last?

Posted by Chris and Dick Dovorany, Broker/Associate at Premiere Plus Realty ( Homes for Sale in Naples, Bonita Springs and Estero, Florida) over 6 years ago

This is the type of class I would love attending. Interesting, necessary and easy to grasp too...thank you

Posted by Richie Alan Naggar, agent & author (people first...then business Ran Right Realty ) over 6 years ago

Reuben, you hit the nail on the head.

Many years ago in the mid 1980's,  I sold Paslode Products in Orange County Florida, including nail guns and staple guns for roofing.  One of the problems that still plagues that industry is the use of generic nails and staples.

They usually are half the price of the factory brand and about half as good. 

Another problem is the fact that although there are ring shank nails available..they are more expensive and most roofers or contractors do not use them.

The particular nail in the photograph is either a Bostitch Coil Nail gun nail or a generic knock off...my money is on the generic.  Either way it is too short for most applications.

This is not exclusive to just roofs.  If you have a floor that squeaks when you walk on it and it is less than 30 years old...chances are that either smooth shank nails or staples...or generics...OR Too short of a nail was used.

You can also see this in sheetrock nail pops.

A minimum of 50% of the nail/staple length needs to penetrate the receiving member after penetrating what it is holding.

IE: 1 1/4" is correct for shingles going into either 1/2 inch or thicker wood ONLY if the shingle depth is 5/8" or less.

If nailing a 2 x 4 into another 2 x 4... a milled (smooth) 2 x 4 is actually 1 1/2" thick...a minimum length of nail is 3".

I see time after time still in 2012 builders, shinglers, remodelers...all using too short of a product...

When you have a client building a home...pay attention to these little details and your buyers will Love you without even knowing it!!

Posted by Mike McCann - Nebraska Farm Land Broker, Farm Land For Sale 308-627-3700 or 800-241-3940 (Mike McCann - Broker, Farmland Broker-Auctioneer Serving Rural Nebraska) over 6 years ago

Reuben, it was my understanding that it was the wood that breaks away when the nail puches through that helps hold the nails from backing out.  Have you ever heard that too?

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

That's an observation on so many inspections!  And then from the inside you can barely see the new nail heads.

Solution:  just set the gun so it shoots the 1"nails harder!  That way they will penetrate through the sheathing further.

Yep, that'll do it!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Most of the problems are very simple to avoid, do it the correct way and there will not be many problems.  Unfortunately in too many cases, either the contractor is trying to save a few pennies or simply doesn't know what he is doing.

Posted by Robert Sole (REM Inspections LLC) over 6 years ago

I have done a bit of roofing in my time.  I had a personwant meto use the short nails and i told him I would not.

He said he would use someone else then.  I told him that was Just fine!

Posted by William Feela, Realtor, Whispering Pines Realty 651-674-5999 No. (WHISPERING PINES REALTY) over 6 years ago

Reuben, great and timely information.  I am having my roof done and will inquire as to what length nails my contractor is using.

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) over 6 years ago

Dorie - thanks.  When it comes to explaining defects, I rely very heavily on photos :)

Michael - I don't know why short shingle nails would even be sold in my area.

Chris and Dick - probably not!

Richie - I've put together a huge powerpoint training seminar for agents on home inspection issues / defects, but I don't have any time to promote the continuing ed class, much less give it.  Some day...

Mike - wow, you certainly know your nails!  Thanks for sharing your knowledge and advice.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

Charles - That's a new one for me.  I might have to put on my Mythbusters shirt and do a little testing on that theory, just for fun.

Jay - great idea!  I've heard staples work great for shingles too ;)

Robert - as with so many issues we find.

William - the client actually wanted you to use short nails?  Interesting.  

I had someone send me an email yesterday, saying that when he used to build houses, it was standard practice to use 7/8" nails on roofs to help prevent condensation in the attic.  All of the nail heads would be the coldest points in the attic and frost would accumulate on the nail heads.  To help prevent condensation, the thinking was that you just use shorter nails.  Old school logic.

Chris - I suggest you have a bunch of shingles spot-checked for proper nailing while the shingles are still 'fresh', and haven't sealed themselves down yet.  It's crazy how often shingles are nailed improperly. 

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

Especially when the pressure is set way, way up!  Gotta hold those babies down tight!  It gets windy out there!

And I would think that wood breaking away would leave less surface area for nail friction.  So that likelihood, to me, seems less likely!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Inspectors usually learn about the nails sticking through the roof deck the first time they stand up to far in an attic.

Posted by Rob Ernst, Reno, NV-775-410-4286 Inspector & Energy Auditor (Certified Structure Inspector) over 6 years ago

Jay - clearly some testing is in order.

Rob - I've had my share of those.  I lost my balance in an attic about two weeks ago and had to throw my arm up to steady myself... got a nice hole in my elbow from that.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

The staple pressure comment was a joke.  The loss of friction due to wood being blown away was not.  It just seems to me that with less surface area there would be less friction, necessarily.  I don't have an idea as to how to test it.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

See that here too. A lot of roofs I look at have short nails. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 6 years ago

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